Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI000000000191

Record: MDI000000000191

General

Mineral Record Identification
Record Name(s) Spring Zone - 1946
Related Record Type
Related Record(s)
Record Status Occurrence
Date Created 2006-Dec-18
Date Last Modified 2022-Oct-11
Created By
Revised By

Commodities

Primary Commodities: Gold



Location

Township or Area: Tarp Lake Area

Latitude: 51° 33' 15.08"    Longitude: -90° 3' 45.93"

UTM Zone: 15    Easting: 703620   Northing: 5715545    UTM Datum: NAD83

Resident Geologist District: Thunder Bay North

NTS Grid: 52O09SE

Point Location Description: Location from assessment file map in AFRO# 2.32421.

Location Method: Data Compilation



Assessment Work on File

Assessment Work on File
Office File Number Online Assessment File Identifier Online Assessment File Directory
2.14584 52O09SE0001 52O09SE0001
2.32421 20000001524 20000001524

Geology

Province: Superior

Subprovince: Uchi

Terrane: North Caribou

Domain: Uchi

Belt: Pickle Lake

Geological Age: Mesoarchean  



Geology Comments

Dec 18, 2006 (Mark Puumala) - The Tarp Lake area gold prospects and occurrences are located in the northern portion of the Pickle Lake Greenstone Belt. These occurrences are found within a mafic metavolcanic rock dominated supracrustal sequence identified by Young (2003) as being part of the > 2860 Ma Pickle Crow Assemblage. According to Young (2003), the Pickle Crow assemblage is dominated by massive and pillowed mafic metavolcanic flows with subordinate (likely synvolcanic) gabbroic sills. MacTavish (2006) describes the mafic metavolcanic flows as being commonly well-foliated to schistose, amphibolitized, and often finely-amygdaloidal. In addition, MacTavish (2006) indicates that the mafic metavolcanics include units of pillow and hyaloclastite breccia. The gabbroic sills are described by MacTavish (2006) as fine- to coarse-grained gabbro, melagabro and ferrogabbro sills up to 200 m thick. The mafic metavolcanics are intercalated with thin, laterally continuous banded iron formation and small, discontinuous lenses of intermediate to felsic metavolcanics. A significant 90 to 125 m thick northeast-trending unit of felsic to intermediate tuff breccia to pyroclastic breccia has been reported in this area by MacTavish. Relatively thin units (up to 70 m thick) of clastic metasedimentary rocks have also been reported by MacTavish (2006). All lithologies are intruded by semi-concordant feldspar porphyry dikes. These dikes are reported by MacTavish (2006) to vary widely in thickness and lateral continuity. MacTavish (2006) also indicates that all lithologies are crosscut by late biotite lamprophyre dikes that are up to 5 m in thickness. One of these dikes is reported to contain ultramafic and country rock xenoliths, red garnets and greenish diopside. Stratigraphy in the Tarp Lake area generally faces toward the northwest, except where asymmetric folding (mainly further to the southeast in the Pickle Crow mine area) has caused reversals in the younging direction (Young 2003). The dominant geological structure in the Tarp Lake area is the Tarp Lake Shear Zone. This structure strikes northeast and forms a wide, diffuse and anastamosing deformation zone that is poorly exposed and characterized (MacTavish 2006). The mafic metavolcanic rocks affected by this shear zone are characterized by moderate to intense carbonatization, sericitization and local silicification (MacTavish 2006). This alteration zone hosts the numerous gold occurrences throughout the area. Many of the more significant gold prospects appear to be located where the Tarp Lake Shear Zone is intersected by splays and/or later fault/shear zones, or relatively competent lithological units such as porphyry intrusions, gabbro and iron formation. The cross-cutting deformation zones are most commonly reported to strike approximately northwest, east-west and north-northeast. Similar complex faulting/shearing patterns have been noted nearby by MacQueen (1987) in the vicinity of the Pickle Crow gold mine, and by McAuley and Winter (1990) in the vicinity of a number of gold occurrences in the July Falls area.




Lithology

Lithology Data
Rock Type Rank Composition Texture Relationship
Mafic lava flow-unsubdivided 1

Mineralization

Mineralization and Alteration
Rank Mineral Name Class Economic Mineral Type Alteration Mineral Type Alteration Ranking Alteration Intensity Alteration Style
1PyriteEconomicOre
AnkeriteAlterationCarbonatization1Medium
SilicaAlterationSilicification2Weak

Mineralization Comments

Dec 18, 2006 (Mark Puumala) - The Spring Zone is described by Potts (1992) as moderately- to highly-sheared and carbonatized mafic metavolcanic rocks. Shearing is oriented 060/80 and increases in intensity toward the southern margins of the surface exposure. The alteration consists of variable ankerite and weak silicification with trace amounts of disseminated pyrite. Potts (1992) indicates that Norpick Gold Mines obtained an assay of 1.51 g/t over 1.22 m from a diamond drill hole advanced through the Spring Zone in 1946.



Mineral Record Details

Classification
RankClassification            
1 Lode (Gold)
Characteristics
Rank Characteristic            
1 Sheared

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For detailed information regarding this mineral record please contact the Thunder Bay North Resident Geologist District Office